Laminates have been employed as surface materials for application to tables, vanities, vertical wall coverings, door coverings, and the like for a number of years. Conventionally, these laminates are prepared by assembling, in superimposed relationship, a core layer which consists of a plurality of kraft paper sheets impregnated with a thermosetting phenol-formaldehyde resin and a decorative sheet that is impregnated with a thermosetting resin which does not undergo noticeable deterioration in color, such as darkening, upon any subsequent laminating operations. Typical resins used in the decorative sheet include, but are not limited to, melamine-formaldehyde resins, epoxy resins, unsaturated polyester resins, and urea resins. The decorative sheet itself is conventionally an alpha-cellulose paper sheet which has been dyed, pigmented or upon which there is imparted some design or pattern. Frequently, superimposed above the decorative sheet there is placed an overlay sheet. The overlay sheet is a highly refined alpha-cellulose paper sheet unpigmented, but impregnated with a color-stable thermosetting resin.
The assembled laminate is heat and pressure consolidated under conventional conditions of pressure and temperature to produce a unitary laminated product. During heat and pressure consolidation, the arrangement of plates, cushions, sheets and the laminate assembly must be such so as to most effectively and uniformly distribute the heat and pressure to the laminate. The cushion in such an arrangement acts to absorb thermal shock and shear stress during pressing thereby aiding the uniform distribution of heat and pressure to the laminate. The cushion employed in this arrangement has traditionally been comprised of a plurality of unimpregnated kraft paper sheets. Cushions of this type at the top of the press pack have an average useful life of 5 pressing runs. When employed at the bottom of the press pack, their useful life has an upper limit of approximately 25 pressing runs. When used at the top of the press pack, their useful life is somewhat shorter due to excessive handling because, after each run, they are inspected for damage. If no damage is discovered, the top-used cushions are either used again as the top cushion or reshuffled into the bottom of the press pack. Because of this, the cost of cushions to the laminating industry is presently approaching three million dollars annually and escalating. Additionally, the conventional kraft cushions currently employed oftimes result in a peripheral gloss around the edges of the laminate, called the picture frame effect, requiring the edges to be trimmed off of the laminates so produced before they are sold. This additional trimming step contributes to the cost of laminate manufacture especially when a paper texturizer has been employed. Occasionally, water marks will also result from the use of these conventional cushions in that the uniformity of the heat and pressure fluctuates when they have been used a number of times.
Thus, there exists the need for a cushion that exhibits a greater useful life and yet continues to effectively and uniformly distribute heat and pressure to the decorative laminate assembly. Accordingly, the provision for a more economical and efficient cushion would fulfill a long-felt need and constitute a significant advance in the art.